Cells of hibernating mammals are compared with those of mammals which do not hibernate to examine basic mechanisms of ion transport and interactions of transport mechanisms which ensure cellular ionic balance. The principal adaptation of hibernators studied so far has been adaptation to low temperature. Past effort has documented the involvement of the Na/K pump and of general leak in this adaptation in several tissues. Future efforts will focus on erythrocytes and hepatocytes. With erythrocytes the purpose will be to define in terms of kinetics and the overall pump reaction the points of failure of the Na/K pump in the cold. In both cell types the several components of "leak" to Na and K will be examined to determine their contribution to loss of ion balance (in non-hibernator) or its retention in the cold (in hibernators) (i.e., electrochemical permeation, Na-K cotransport, Ca-sensitive to channel, amino acid-Na cotransport). Another adaptation of many hibernators is seasonal inanition and self-starvation. The likelihood that reduction of ion turnover at the cell membrane is a source of energy conservation during starvation in hibernators and non-hibernators will be explored. The perceived areas of health-relatedness are, for the low temperature studies, improved viability of cells during organ storage and, for the seasonal/inanition studies, cellular adaptation to and effects of undernutrition.